Ammunition comprises two main components, namely projectile and primed cartridge case; the projectile further comprises a fuze and shell body. One type of fuses commonly used in ammunition is impact fuze that detonates the ammunition by the resultant impact from the hitting of the ammunition to its target. However, when ammunition with an impact fuze is delivered, it may fail to explode due to insufficient impact. The insufficient impact may be caused by a variety of reasons including: (1) it misses the target and lands on soft grounds such as a swamp or a snow covered area; or (2) it lands on a suboptimal angle with respect to the point of impact. Unexploded ammunition poses hazards for the civilians and the military alike and operation to remove such unexploded ammunition is dangerous, costly and labor intensive.
Self destructing impact fuses are employed to detonate ammunition delivered with projectiles when the ammunition fails to explode upon impact. Prior art self destructing impact fuses can be generalized into three categories: (1) chemical, (2) mechanical and (3) electronic. Exemplary of a chemical self destructing delay impact is U.S. Pat. No. 3,998,164 issued to Hadfield. '164 described a self destructing fuze illustrating the use of a timing chamber containing liquid in combination with a weight and tubular spring mechanism for releasing the firing pin onto the detonator.
An example of a mechanical self destructing fuze for sub-munition is U.S. Pat. No. 4,653,401 issued to Gatti. '401 relies on the plastic deformation of a wire element which holds and delays the exertion of a secondary striker member onto the detonator.
Recently electronic self destructing fuses are also developed to detonate projectiles via electronic timing circuitry after they fail to explode upon impact.
The inventors of the present invention have disclosed a self destructing impact fuze in U.S. Pat. No. 6,237,495, where the disclosed self destructing impact fuze incorporated into a self destructing impact fuze the key components which respond to physical forces exerted on the ammunition during the flight of the projectiles, resulting in the enhanced reliability of self destructing fuze without significantly increasing the unit production cost. However, the disclosed self destructing impact fuze is not functioning as well in low velocity projectiles as in high velocity projectiles. Therefore, there is a need to have a self destructing impact fuze that can function reliably in low velocity projectiles.